Primary rainbow of high refractive index particle (1.547<n<2) has refraction ripples

Primary rainbow (Debye series, p=2) of a common liquid droplet, i.e., water drop, has a smooth Airy rainbow structure, and the superimposed high frequency ripple structures are mostly generated by interference of refraction (p=2) and reflection (p=0). In this work, the primary rainbow (p=2) of a particle with high refractive index (1.547